You were close, it's called melatonin. It's actually been my sleep med of choice for years, specifically because it's non-habit forming and doesn't work like any other sleep med that exists. Instead of sedating you, it works by affecting your circadian rhythms, essentially telling your brain that it's time to go to sleep without forcing your brain to actually do so.
There's a couple different doses out there, most commonly 0.1mg, 1mg, 3mg, and 5mg. 0.1mg is really only for jetlag, I find that 3mg taken one to two hours before bed works the best. Unlike most medicines, taking more won't make you more tired, you have to find your "sweet spot." And as a sidenote, melatonin has a very interesting side effect in that it will make your dreams far more vivid and weird. Hope that it helps out